Carrier current control system



Feb. 12, 1946. p B, KORNEKE JR 2,394,786

CARRIER CURRENT CONTROL SYSTEM Filed Oct. 24, 1942 Inventor: Paul B.Korneke Jrx,

His Attorney Patented Feb. 12, 1946 CARRIER CURRENT CONTROL SYSTEM PaulB. Korneke, Jr., Scotia, N. Y., assignor to General Electric Company, acorporation of New York Application October 24, 1942, Serial No. 463,177

Claims.

My invention relates to frequency selective systems and moreparticularly to carrier current control systems and means associatedwith such systems for controlling remote loads.

Carrier current systems have been used in connection with power systemsfor controlling the application of a plurality of distant electricalenergy consuming devices, such as hot water heaters and street lightingloads, for example.

In one form of carrier current control, relays are employed which aredesigned to operate in one direction, as for closing a set of contacts,after the transmission of current through the operating winding of therelay for a predetermined time and to cause a different operation, as toopen the contacts, upon the receipt of a longer pulse.

One form of device for accomplishing the above purpose comprises aswitch control member adapted to be actuated between two positions by athermostatic member which is energized by a heater connected across thesupply source and controlled in direction of movement by variations inthe time interval of received carrier current frequency impulses. Asuitable switch operator is described in application Serial No. 385,278to J. L. Woodworth, and assigned to the same assignee as the presentinvention. The thermostatic device therein described and claimedcomprises a strip or bar having two sections endto-end and a heatingwinding so arranged that in order to operate a switch a heating currentis transmitted for a predetermined time in order to cause the strip tobend in a direction to close the contacts. In order to open the switchcontacts, a second impulse of a longer time duration is sent over thepower lines in order to cause the heating winding of the relay again tobe energized. The longer impulse causes the heating coil to providesufficient heat to reverse the direction of the bending force of theswitch arm from that in the closing operation. After a predeterminedtime the bending is sufficiently great to pull the contact arm away fromthe other relay contact and open the circuit associated therewith.

It may be desired to control a large number of different types ofdevices on a power system by transmitting different frequencies todifferently tuned resonant circuits. If frequencies relatively closetogether are chosen there may be interference and faulty operation ofdevices. Operation of adjacent power circuits, harmonics, as fromfluorescent lamps in the vicinity of a device, and premeditated andunauthoried operation are undesirable. It is an object of my inventionto provide a new and improved carrier current control system in whichfaulty operation caused by interference from within, as well as without,the power system, unauthorized operations, etc., are eliminated or atleast minimized.

The novel features which I believe to be characteristic of the inventionare set forth with particularity in the appended claims. My inventionitself, both as to its organization and manner of operation, togetherwith further objects and advantages thereof may best be understood byreference to the following description taken in connection with theaccompanying drawing in which Figs. 1 to 4 inclusive show variousembodiments of my improved carrier current control system.

In carrying out my invention I utilize a resonant circuit for enablingselection of the device to be operated. There is provided meansresponsive to the receipt of one frequency for rendering the resonantcircuit temporarily responsive to a different frequency and the deviceto be operated can be controlled only following the receipt of thesecond frequency. Thus, at least two frequencies are necessary tocontrol the device. Similarly, I contemplate the transmission of atleast one frequency for restoring the device to its original conditionor for operating the device to the opposite condition. My invention isnot limited to the use of two frequencies for one operation and onefrequency for the reverse operation and I will describe circuitarrangements in which at least two frequencies are necessary foroperating a device to one condition and one and two frequencies foroperating the device to a different condition.

Referring to Fig. 1, there is illustrated a remote control systemincluding a suitably energized electric power supply line H). Inasmuchas the source of supply forms no part of my present invention it isbelieved unnecessary to describe and illustrate details of the source ofsupply. There are illustrated two sources 20 and 2| of carrier currentof different frequency, as 500 and 1000 cycles, respectively, forexample. The power line is adapted to transmit electrical energy tovarious electrical loads such as those indicated by the numerals H andI2. The load II is shown connected directly to the line and, of course,is energized at any time the line I0 is energized. The load [2, however,is arranged to be operated according to the transmission ofpredetermined carrier current frequencies over the line H). There isprovided a load switch l3 for connecting the load l2 to the power line10. Thus the load |2 is connected to one side of the power line by aconductor l4 and to the other side of the power line by means ofconductors |5, contacts l5 and l! of the switch l3, the arm |8 of theswitch l3, and a conductor I9. There is provided a series resonantcircuit 22 comprising a capacitor 23 and an inductance 24 arranged to beconnected across the line It]. One side of the resonant circuit isconnected to the conductor H and the other side is connected to theconductor l9 through contact 25 and the arm |8 of the switch |3 whichnormally connects the resonant circuit across the line. Now if it beassumed that the resonant circuit is normally tuned to 500 cycles, itwill be apparent that upon the transmission of a 500 cycle carriercurrent impulse a 500 cycle current flows through the series resonantcircuit. The inductance 24 may be the winding of a relay 26 having anarmature 21 arranged to bridge electrically the contacts 28 when therelay is energized. Thus, when the resonant circuit 22 is passingsufficient current to pick up the relay 26, the contacts 28 will bebridged to connect the heating coil 29 of the switch |3 across the lineH].

The switch 13 may be a thermally operated device such as that describedin the above mentioned Woodworth application according to which the armI8 is a strip which is caused to bend first in one direction and then inthe other depending upon the length of the heating period. The 500 cycleimpulse if continued a sufficient time, as seconds, for example, willcause sufficient heating of the thermal arm l8 to cause the arm to moveupwardly as viewed in Fig. 1 to disconnect the resonant circuit from theline and deenergize the relay 26. However, the heat lag associated withsuch a thermally operated switch will be sufficient to carry the arm l8over until it engages the contact 30 which is connected by means of aconductor 3| to a tap on the inductance 24 and thereby changes theresonant frequency of the series circuit. If the new resonant frequencyis 1000 cycles the relay is again operated upon the receipt of a 1000cycle impulse transmitted from the 1000 cycle source. Again currentpasses through the heater coil 29 and causes the arm I to bend furtherinto engagement with the load contact [6 and thereby connect the load tothe line. Thus there is provided means responsive to the receipt ofcarrier current of one frequency for preparing the load connecting meansfor the closing operation and responsive to the second frequency forconnecting the load to the line or, in other words, to complete theclosing operation.

Throughout the period of energization of the load |2 the switch I3 isheld in engagement with the contacts l5 and 30 by means of the magnet|8a so that the resonant circuit remains tuned to the second frequencyor 1000 cycles. Therefore, in order to disconnect the load l2, it isnecessary to send out a 1000 cycle impulse of sufficient duration tocause the arm l8 to be heated sufficiently to pull away from the magnetand bend away from the contacts l6 and 30. As the arm cools to normaltemperature, it will assume its normal position with the arm engagingcontact 25, and the resonant circuit 22 is again tuned to 500 cycles.

In Fig. 2 there is illustrated a different embodiment of the invention.Similar devices are indicated by the same numerals used in thediscussion of Fig. 1. In this embodiment of my invention there isemployed a thermal switch 32 which may have a bimetallic arm 32a whichnormally engages the contact 33 for establishing a series resonantcircuit across the line l0 through the condenser 23, the rela coil 24,contact 33. arm 32a and a conductor 35. If the same frequencies are usedto operate the thermal switch 34, a 500 cycle impulse will cause relay24 to be energized to bridge the contacts 28 and connect the heatingcoil 36 of the switch 32 and the heating coil 3! of the switch 34 acrossthe line H]. Switch 34 is preferably of the same type as switch l3.After a current fiow for a predetermined time, the arm of the switch 32bends out of engagement with the contact 33 and deenergizes the relay24. The heat lag carries the arm over until it makes contact with theswitch contact 38. thereby connecting one side of the line to theintermediate tap on the coil 24 and thereby retuning the resonantcircuit to a different frequency as 1000 cycles, for example. Upon thereceipt of a 1000 cycle impulse the switch or relay 22 is againenergized to close the contacts 28 to permit current to pass through theheating coils 36 and 31. If the 1000 cycle impulse continuessufficiently long the heating coil 31 causes the arm of the thermalswitch 34 to be moved into engagement with the load contacts and therebyplaces the load |2 across the line H). Upon the termination of the 1000cycle impulse the relay 24 is deenergized thereby deenergizing theheating coils 3G and 31 and the arm of the thermal switch 32 moves toits normally closed position in engagement with the contacts 33.

In order to open the switch 34 an impulse of proper frequency must againbe sent along the power line. Inasmuch as the whole of the coil 24 isagain included, the circuit is again resonant to 500 cycles and the 500cycle current closes the relay permitting heating current to flow. Aftera predetermined time, as ten seconds, the arm 32a moves into engagementwith the contacts 38, and thereby conditions the resonant circuit forthe opening operation. Upon receipt of a 1000 cycle impulse relay 24again picks up to energize the heating coils 36 and 31 and if the pulsebe continued a suflicient time such as 40 seconds, for example, the armof the thermal switch 34 will be heated until it bends away from theload contact with which it is associated and thereby opens the loadcircuit. Thus in this arrangement of my invention two frequencies areneeded to operate the relay for both closing and opening conditions.

In Fig. 3 there is shown another embodiment of my invention whichrequires two frequencies to close and two frequencies to open a switch.The circuits shown in Figs. 1 and 2 depend upon time lag in the bendingof the thermal responsive arm of the switch. This condition iseliminated in the arrangement shown in Fig. 3. In this form of theinvention there is provided a pair of series-connected condensers 39 and40 in series with the coil 24. A thermal switch 4| having a thermallyresponsive arm 4|a is arranged to shunt the condenser 40 when the armengages contact 45. If it be assumed that the condensers and coil 24 arechosen to resonate at 1000 cycles, upon receipt of a 1000 cycle impulsethe relay 24 will be energized to cause the contacts 28 to be bridgedfor completing a heating circuit through the heating coils 42 and 31 ofthe thermal switches 4| and 34 respectively. The heating current causesthe arm 4|a to bend into engagement with the contact 45. The thermalcapacities of the switches 4| and 34 are chosen so that when the arm 4|a engages the contact 45 to short out the condenser 40 the arm 34b. hasmade no appreciable movement; toward its load contact. Upon shorting outthe condenser 40 the capacity in the resonant circuit is greater andtherefore the resonant frequency of the series circuit is less. Thenupon receipt of the lower frequency, as 500 cycles, the relay 24 isagain energized to permit the contact arm of the switch 34 to be heatedup suflicientlyto close the load circuit. After the impulse ceases, thearm 4Ia returns to its normal position and opens the contact 45, aga ntuning the circuit to resonate at 1000 cycles while the arm 34a is heldin its circuit closing position by the magnet l8a. A similar actiontakes place for opening the circuit except that the 500 cycle impulsemust be continued long enough to cause arm 34a to bend away from theassociated contact.

In Fig. 4 there is illustrated a circuit which is somewhat similar tothat describer in connection with Fig. 3. The circuit differs, however,in the provision of parallel instead of series-connected condensers.Thus the resonant circuit under normal conditions comprises a condenser46 and the coil 24. However, upon receipt of the first frequency impulsethe thermally responsive switch 41 is closed to place a condenser 48 inparallel with the condenser 46 thereby increasing the capacity of theresonant circuit and thereby decreasing the resonant frequency of thecircuit. The condenser 48 is illustrated as a variable condenser andmay, for example, be provided with a screw adjustment to permit tuningthe circuit to a desired frequency.

While I have described the operation of this invention as utilizing twofrequencies to cause one type of operation and one or two frequenciesfor the reverse operation, it will be apparent that by employing aplurality of taps on the coil 24 or by employing more than twocondensers or by both means a larger number of frequencies may berequired to operate the system. Moreover, while it may be mostconvenient to impress the plurality of frequencies on the power line atthe same time such arrangement is not necessary and the conditioning orpresetting frequency may be sent first and followed at a later time bythe operating frequency. With the latter arrangement, a variable speedgenerator might be employed. It will be-recognized that the secondfrequency impulse must be transmitted before the thermal switches arepermitted to cool sufficiently to break the operation establishingcircuit.

While I have shown a particular embodiment of my invention, it will beobvious to those skilled in the art that changes and modifications maybe made without departing from my invention in its broader aspects, andI, therefore, aim in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. A frequency selective system comprising a member adapted by operatingin a progressive manner in response to a control impulse of givenduration to perform a circuit controlling operation, means fortransmitting a plurality of impulses of different frequencies, aresonant circuit tuned to one of said frequencies and receiving saidplurality of frequencies, means associated with said resonant circuitand operasaid one frequency for applying a control impulse to saidmember to start its progressive operation, means also responsive to saidcontrol impulse for interrupting the application of said control pulseto said member prior to said predetermined duration and thereby preventthe progressive operation of the member to find circuit controllingcondition and for changing for a predetermined period said resonantcircuit to resonate at a different frequency, said means associated withthe resonant circuit then operating in response to the differentfrequency for applying an additional control impulse to said memberduring the presence of said second frequency, said member operating inits progressive manner in response to said additional impulse if of apredetermined duration to finally complete the circuit controllingoperation, said member including means for returning it to normalcondition if the second impulse is not maintained for a sufficient timeto cause its progressive operation to circuit controlling position andfor returning it to normal condition during the predetermined time ofthe changed tuning from the first to second frequency if the secondfrequency is not present.

2. A frequency selective system comprising a unitary device adapted foroperation in a progressive manner in response to control impulses ofdifferent predetermined frequencies to perform a circuit controllingoperation, means for transmitting said different predeterminedfrequencies, a resonant circuit tuned to one of said frequencies andassociated with said device, operating means associated with saidresonant circuit and responsive to the receipt thereby of an impulsefrequency to which the same is resonant for effecting progressiveoperation of said device, means responsive to a predetermined durationof said impulse frequency for interrupting the progressive operation ofsaid device prior to completion thereof and for temporarily changingsaid resonant circuit to resonate at a different frequency, saidoperating means being thereby rendered temporarily responsive to asucceeding impulse of another of said different frequencies having apredetermined duration suflicient for causing further progressiveoperation of said device.

3. A frequency selective system comprising a device having an operatingmember arranged for progressive operation in response to sequen tialcontrol pulses of predetermined discrete frequencies to perform acircuit controlling operation, means for supplying to said device pulsesat said discrete frequencies, means including a resonant circuitnormally tuned to one of said frequencies for applying a presettingimpulse to said member to start the progressive operation of saidmember, means responsive to partial operation of said member forrendering said resonant circuit non-responsive to said one frequencythereby to interrupt said presetting impulse prior to complete operationof said member, means controlled by said partial movement of said memberfor rendering said resonant circuit temporarily responsive to a secondof said frequencies, and means including said temporarily tuned resonantcircuit for applying a second control impulse to said member to causefurther progressive operation thereof.

4. In a remote control system. a device having a thermal responsivemember adapted by operative in response to the receipt of impulses of ti a p o essive man t perform a uit controlling operation in response tocontrol pulses at predetermined discrete frequencies, a resonant circuitnormally tuned to one of said frequencies, a relay controlled by saidcircuit and responsive to a pulse at said one frequency for applying acontrol impulse of predetermined duration to said thermal responsivemember to effect predetermined partial operation thereof, and meansresponsive to said partial operation of said thermal responsive memberfor rendering said relay temporarily non-responsive to said onefrequency and responsive to a second frequency prior to completeoperation of said member, whereby said relay is conditioned to apply acontrol impulse to said thermal member in response to a pulse at saidsecond frequency within a predetermined time after said first pulsethereby to cause further progressive operation of said member.

5. In a remote control system in which succeeding pulses of differentfrequencies are transmitted to a remote point to effect a desiredoperation at said point, means at said point responsive to said pulsesto operate a member from one position through a second position to athird position, said means including a circuit normally tuned to thefrequency of the first pulse and in which said pulses are received,means responsive to receipt of said first pulse in said circuit tooperate said member from said first position to said second position andto tune said circuit to the frequency of the second pulse. meansresponsive to receipt of the second pulse to operate said member fromthe second position to the third position, and means responsive tooperation of said member to the third position to effect said desiredoperation.

PAUL B. KORNEKE, Jr.

Certificate of Correction Patent No. 2,394,786.

February 12, 1946.

PAUL B. KORNEKE, JR.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 3,second column, line 7, claim 1, for the word find read final and thatthe said Letters Patent should be read with this correction therein thatthe same may conform to the record of the case in the Patent Signed andsealed this 22nd day of October, A. D. 1946.

LESLIE First Assistant Gammissionei of Patents.

